Re: [PATCH v2] drivers/net/wan/lapbether: Use needed_headroom instead of hard_header_len

[Xie He]

Hi Martin,

I'm currently working on a plan to make all X.25 drivers (lapbether.c,
x25_asy.c, hdlc_x25.c) to set dev->hard_header_len /
dev->needed_headroom correctly. So that upper layers no longer need to
guess how much headroom a X.25 device needs with a constant value (as
they currently do).

After studying af_packet.c, I found that X.25 drivers needed to set
needed_headroom to reserve the headroom instead of using
hard_header_len. Because hard_header_len should be the length of the
header that would be created by dev_hard_header, and in this case it
should be 0, according to the logic of af_packet.c.

So my first step is to fix the settings in lapbether.c. Could you
review this patch and extend your support via a "Reviewed-by" tag? If
this can be fixed, I'll go on and fix other X.25 drivers. Thanks!

It's very hard to find reviewers for X.25 code because it is
relatively unmaintained by people. I hope I can do some of the
maintenance work. I greatly appreciate your support!